Internal combustion engine with plate-mounted cam drive system

ABSTRACT

An internal combustion engine for a vehicle, such as a motorcycle, includes a crankcase, two banks of cylinders projecting from the crankcase in a 56-57 degree V-configuration, a plurality of pushrods, and a plurality of camshafts supported by the crankcase. The two banks of cylinders include a first cylinder bank that projects from the crankcase to a first cylinder head, and a second cylinder bank that projects from the crankcase to a second cylinder head. The plurality of intake and exhaust valve pushrods extend between the crankcase and the first and second cylinder heads, driven by one intake camshaft and two exhaust camshafts.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuing application of U.S. Ser. No.13/181,967, filed Jul. 13, 2011, entitled “VEHICLE AND PROPULSION SYSTEMINCLUDING AN INTERNAL COMBUSTION ENGINE,” now issued as U.S. Pat. No.______, issued on ______. U.S. Ser. No. 13/181,967 is a continuingapplication of U.S. Ser. No. 12/481,195, filed Jun. 9, 2009, entitled“VEHICLE AND PROPULSION SYSTEM INCLUDING AN INTERNAL COMBUSTION ENGINE,”now issued as U.S. Pat. No. 8,011,333 issued on Sep. 6, 2011. U.S. Ser.No. 12/481,195 is a continuing application of U.S. Ser. No. 11/667,999,filed Oct. 5, 2007, entitled “VEHICLE AND PROPULSION SYSTEM INCLUDING ANINTERNAL COMBUSTION ENGINE,” now issued as U.S. Pat. No. 7,703,423,issued on Apr. 27, 2010, which claims benefit of and priority toInternational application PCT/US2005/041876 (published as WO2006/083350,filed Nov. 18, 2005) entitled “VEHICLE AND PROPULSION SYSTEM INCLUDINGAN INTERNAL COMBUSTION ENGINE,” and provisional application Ser. No.60/628,541 (filed Nov. 18, 2004) entitled “MOTORCYCLE ENGINE,” theentire contents of all of which are incorporated herein by reference intheir entirety.

BACKGROUND

The present invention relates generally to vehicles having internalcombustion engines, and more specifically, to an internal combustionengine propelled motorcycle.

A motorcycle is a two-wheeled vehicle powered by an engine. The wheelsare in-line, and at higher speed the motorcycle remains upright andstable by virtue of gyroscopic forces; at lower speeds readjustment ofthe steering by the rider gives stability. The rider sits astride thevehicle on a seat, with hands on a set of handlebars which are used tosteer the motorcycle, in conjunction with the rider shifting his weightthrough his feet, which are supported on a set of “footpegs” or “pegs”which stick out from the frame. The chassis or frame of a motorcycle istypically made from welded struts, with the rear suspension often beingan integral component in the design.

The engine of the motorcycle typically sits under a fuel tank, betweenthe rider's legs. Typically, motorcycle engines displace between aboutthree cubic inches (approximately 50 cubic centimeters) and 140 cubicinches (approximately 2300 cubic centimeters) and have one to fourcylinders arranged in a “V” configuration, an in-line configuration, ora boxer configuration. In most one-cylinder motorcycle engines, thecylinder points up and slightly forward with a spark plug on top. Themost common configuration for two-cylinder motorcycle engines is a“V-twin” where the cylinders form a “V” around the crankshaft, which isoriented transversely i.e., perpendicular to the direction of travel).Typically, the angle of the “V” is 90 degrees. Other knownconfigurations for two-cylinder motorcycle engines include a “paralleltwin” (i.e., in-line configuration) where the cylinders are parallel,and a “boxer twin” (also called a “flat-twin”) where the cylinders arehorizontally opposed, and protrude from either side of the frame.Four-cylinder engines are most commonly configured in-line, although “V”and square configurations are also known. Although less common,motorcycle engines having three, six, eight, and ten cylinders areknown.

Motorcycle engines are typically cooled either with air or water.Air-cooled motorcycle engines rely on ambient air flowing over theengine to disperse heat. The cylinders on air-cooled motorcycle enginesare designed with fins to aid in this process. It is believed thatair-cooled motorcycle engines are cheaper, simpler, and lighter thanwater-cooled motorcycle engines, which circulate water between a waterjacket surrounding the combustion chamber(s) and a radiator thatdisperses heat transferred from the engine via the circulating water.The operation of motorcycle engines may either be two-stroke orfour-stroke. It is believed that two-stroke engines are mechanicallysimpler and may be lighter than equivalent four-stroke engines. Butfour-stroke engines are believed to operate more cleanly, be morereliable, and deliver power over a much broader range of engine speeds.Rotation of the engine crankshaft is transferred to a transmission, viaa clutch and a primary drive. Most motorcycle transmissions have five orsix forward gears; only a few motorcycle transmissions are fitted with areverse gear. The clutch is typically an arrangement of plates stackedin alternating fashion, one geared on the inside to the engine, and thenext geared on the outside to the engine output shaft. Whether wet(rotating in engine oil) or dry, the plates are squeezed together by aspring, causing friction buildup between the plates until they rotate asa single unit, thereby driving the transmission via the primary drive.Releasing the clutch spring allows the engine to freewheel with respectto the engine output shaft. The primary drive couples the engine outputshaft to an input shaft of the transmission and typically includeseither a toothed belt or a chain. A secondary or final drive from thetransmission to the rear wheel of a motorcycle typically includes achain, although final drives may alternatively include a toothed belt oran enclosed torque shaft in combination with right-angle drive gearing.

Motorcycle manufacturers often also produce all-terrain vehicles orATVs. These have two or more back wheels, usually two front wheels, anopen driver's seat, and a motorcycle-type handlebar. The 4-wheeledversions are also called “quads,” “four-wheelers,” “quad bikes,” or“quad cycles.” ATVs are often used off-road for recreation and utility.Recreational ATVs are generally small, light, two-wheel-drive vehicles,whereas utility ATVs are generally bigger four-wheel-drive vehicles withthe ability to haul small loads on attached racks or small dump beds.Utility ATVs may also tow small trailers. Utility ATVs with six wheelsinclude an extra set of wheels at the back to increase the payloadcapacity, and can be either four-wheel-drive (back wheels driving only)or six-wheel-drive.

Other types of vehicles that use similar engine technology may includeamphibious all terrain vehicles, snowmobiles, personal watercraft, andlight-sport aircraft. An amphibious all terrain vehicle (AATV) typicallyhas four, six, or eight wheels, uses a skid-steer steering system, andthe rider sits inside a chassis. Generally designed to float, AATVs cango through swamps as well as traverse dry land. A snowmobile is a landvehicle that is propelled by one or two rubber tracks, with skis forsteering. Snowmobiles are designed to be operated on snow and ice, butmay also be operated on grass or pavement. A personal watercraft, orPWC, is a recreational watercraft that the rider sits or stands on,rather than inside of, as in a boat. Typically, personal watercraft hasan inboard engine driving a pump jet, and is designed for one to fourpassengers. Light-sport aircraft, which are single or two-seatlightweight, slow-flying airplanes, include “ultralights” that areessentially an engine-propelled hang-glider-style wing below which issuspended a three-wheeled cart for the pilot. An ultralight iscontrolled by shifting the pilot's body weight with respect to ahorizontal bar in roughly the same way as a hang-glider pilot flies.

SUMMARY OF THE PRESENT INVENTION

In one aspect of the present invention, an internal combustion enginecomprises at least two cylinders, a piston in each of the cylinders, acrankshaft for moving the pistons, a crankcase containing thecrankshaft, three camshafts, and a cam chest intermediate platesupporting the camshafts. The engine further includes a drive system forrotating the camshafts including a camshaft cogwheel on each of thecamshafts, a pinion cogwheel on the crankshaft, and at least one timingdrive component driven by the pinion cogwheel and driving the camshaftcogwheels.

In another aspect of the present invention, an internal combustionengine comprises at least two cylinders each defining an associatedlongitudinal direction and combining to define a V-shape, a piston ineach of the cylinders, a crankshaft for moving the pistons, a crankcasecontaining the crankshaft, three camshafts, and a cam chest intermediateplate supporting the three camshafts and the crankshaft. The enginefurther includes a valve train system including tappets and pushrodsengaging the three camshafts, rocker arms engaging the pushrods, andintake and exhaust valves engaging the rocker arms, the intake andexhaust valves being operably connected to an associated one of the atleast two cylinders; the pushrods extending in a direction parallel tothe longitudinal direction of the associated cylinder; and a drivesystem driven by the crankshaft for rotating the three camshafts.

In another aspect of the present invention, an improvement is providedfor an internal combustion engine having cylinders, pistons, acrankshaft for moving the pistons, and camshafts for moving valvescontrolling fluid flow into and out of the cylinders. The improvementcomprises the camshafts including three camshafts, and a cam chestintermediate plate supporting the camshafts; the intermediate platebeing attached to a camshaft portion of the engine.

These and other aspects, objects, and features of the present inventionwill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate presently preferred embodimentsof the invention, and, together with the general description given aboveand the detailed description given below, serve to explain features ofthe invention.

FIG. 1 is a first cross section view of a V-configuration internalcombustion engine according to a preferred embodiment.

FIG. 2 is a second cross section view of the V-configuration internalcombustion engine illustrated in FIG. 1.

FIG. 3 is a third cross section view of the V-configuration internalcombustion engine illustrated in FIG. 1. FIG. 4 illustrates a56.25-degree angle of a V-configuration internal combustion engineaccording to a preferred embodiment.

FIG. 5 is an exploded view of a long block for a V-configurationinternal combustion engine according to a preferred embodiment.

FIG. 6 is an isometric view of a cylinder for a V-configuration internalcombustion engine according to a preferred embodiment.

FIG. 7 is an isometric view of a cylinder head assembly for aV-configuration internal combustion engine according to a preferredembodiment.

FIG. 8 is an exploded view of the cylinder head assembly illustrated inFIG. 7. FIG. 9 is a top view of a cylinder head for a V-configurationinternal combustion engine according to a preferred embodiment.

FIG. 10 is a bottom view of the cylinder head illustrated in FIG. 9.

FIG. 11 is a cross section view taken along line A-A in FIG. 10.

FIG. 12 is a cross section view taken along line B-B in FIG. 9.

FIG. 13 is a cross section view taken along line C-C in FIG. 9.

FIG. 14 is a cross section view taken along line H-H in FIG. 9.

FIG. 15 is a cross section view taken along line J-J in FIG. 9.

FIG. 16 is an isometric view of a split main bearing for aV-configuration internal combustion engine according to a preferredembodiment.

FIG. 17A is a bottom view illustrating a mounting arrangement of aV-configuration internal combustion engine according to a preferredembodiment.

FIG. 17B is a drive-side view illustrating relative dimensions of aV-configuration internal combustion engine according to a preferredembodiment.

FIG. 18 is an isometric view of an engine-to-transmission interface fora V-configuration internal combustion engine according to a preferredembodiment.

FIG. 19 is an isometric view illustrating a portion of anengine-to-transmission mounting plate for a V-configuration internalcombustion engine according to a preferred embodiment.

FIG. 20 is an exploded view of a crankshaft with a bolt on mass for aV-configuration internal combustion engine according to a preferredembodiment.

FIG. 21 is a schematic illustration of a connecting rod for aV-configuration internal combustion engine according to a preferredembodiment.

FIG. 22 is an isometric view illustrating a first embodiment of acrankshaft position sensor for a V-configuration internal combustionengine according to a preferred embodiment.

FIG. 23 is an isometric view illustrating a first embodiment of acrankshaft position sensor for a V-configuration internal combustionengine according to a preferred embodiment.

FIG. 24A is a side view of a valve train for a V-configuration internalcombustion engine according to a preferred embodiment.

FIG. 24B is a front view of the valve train illustrated in FIG. 24A.

FIG. 24C is a top view of the valve train illustrated in FIG. 24A.

FIG. 25 is a schematic illustration of a camshaft drive system for aV-configuration internal combustion engine according to a preferredembodiment.

FIGS. 25A-25C are perspective views of an alternative camshaft beltdrive system, FIG. 25A showing intermeshing cogwheels (gears) oncamshaft ends in a partial engine assembly, FIG. 25B showing a modifiedarch-forming camshaft support plate supporting one end of the threecamshafts and partially covering an end of the illustrated engine, andFIG. 25C showing the crankshaft-to-camshaft belt drive similar to FIG.25B but with a modified camshaft support plate supporting the threecamshafts and covering a complete end of the engine.

FIG. 26 is a side view of the camshaft drive system illustrated in FIG.25.

FIG. 27A is a cogwheel-side perspective view of a cam chest intermediateplate for a V-configuration internal combustion engine according to apreferred embodiment. FIG. 27B is a camshaft-side perspective view ofthe cam chest intermediate plate illustrated in FIG. 27A.

FIG. 28 is a cross section view of an induction system for aV-configuration internal combustion engine according to a preferredembodiment.

FIG. 29 is an isometric view of an engine control unit mounted to anintake manifold for a V-configuration internal combustion engineaccording to a preferred embodiment.

FIG. 30 includes (front and rear) isometric views of a housing of an oilpump for a V-configuration internal combustion engine according to apreferred embodiment.

FIG. 31 is an isometric view of a lubrication system oil pump for aV-configuration internal combustion engine according to a preferredembodiment. FIG. 32A is a hidden line plan view of lubricant supplypassages that are cast into a crankcase for a V-configuration internalcombustion engine according to a preferred embodiment.

FIG. 32B is a hidden line perspective view of the lubricant supplypassages shown in FIG. 32A.

FIG. 33 is a partial cross section view of an oil filter mount and oilpressure sending unit for a V-configuration internal combustion engineaccording to a preferred embodiment.

FIG. 34 is a schematic illustration of pushrod tubes for aV-configuration internal combustion engine according to a preferredembodiment.

FIG. 35 is an isometric view of a reed valve for a V-configurationinternal combustion engine according to a preferred embodiment.

FIGS. 36A and 36B are opposite side views of a motorcycle including aV-configuration internal combustion engine according to a preferredembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIGS. 1-3, a preferred embodiment of an internalcombustion engine 300 uses one or more reciprocating pistons 310 (twoare illustrated) and works according to a four-stroke pumping processknown as the Otto cycle. According to the preferred embodiment,reciprocating pistons 310 a and 310 b are disposed in respectivecylinders 320 a and 320 b. Intake valves 330 a and 330 b are opened toallow air (and fuel) to be pulled into the respective cylinder 320 a,320 b as the corresponding piston 310 a, 310 b moves away from cylinderheads 340 a and 340 b. This is commonly referred to as the intakestroke. The intake valves 330 a, 330 b are closed either before orduring movement of the pistons 310 a, 310 b toward the respectivecylinder heads 340 a, 340 b to compress the air (and fuel) in thecylinders 320 a, 320 b, i.e., the compression stroke. If fuel is notmixed with the air, fuel can be directly injected into the cylinders 320a, 320 b and a spark is introduced before, at, or after top-dead-center,i.e., when a piston 310 reaches a position closest to its cylinder head340. The air/fuel charge burns creating increased pressures within thecylinders 320 a, 320 b, forcing the pistons 310 a, 310 b away from theircylinder heads 340 a, 340 b and creating work, i.e., the power stroke.Exhaust valves 332 a and 332 b open before, at, or afterbottom-dead-center, i.e., when a piston 310 reaches a point furthestaway from its cylinder head 340, allowing some of the combustion gasesto escape. The pistons 310 a, 310 b then move towards the cylinder heads340 a, 340 b pushing out the majority of the remaining combustion gases,i.e., the exhaust stroke. The exhaust valves 332 a, 332 b are closedbefore, at, or after the pistons 310 a, 310 b reach top-dead-center, andthe intake valves 330 a, 330 b are opened either before or after theexhaust valves 332 a, 332 b are closed. This pumping process repeatsover the course of every two rotations of a crankshaft 350 connected tothe pistons 310 a, 310 b.

Camshafts 360 a, 360 b and 360 c dictate the movement of the intakevalves 330 a, 330 b and the exhaust valves 332 a, 332 b. The camshafts360 a, 360 b, 360 c force tappets 362 to force pushrods 364 to forcerocker arms 366 to force the intake valves 330 a, 330 b and the exhaustvalves 332 a, 332 b open against the force of valve springs 368. Thislinkage of components is commonly referred to as the valve train.

The pumping processes associated with the cylinders 320 a, 320 b are outof phase with respect to one another such that ignition of a chargeoccurs, alternatingly between the cylinders 320 a, 320 b, once everyrotation of the crankshaft 350.

Features of the present invention will now be described with regard topreferred embodiments of: a shell of the internal combustion engine 300,a power system of the internal combustion engine 300, a valve train ofthe internal combustion engine 300, a valve train drive system of theinternal combustion engine 300, an induction system of the internalcombustion engine 300, and a lubrication system of the internalcombustion engine 300.

Shell of the Internal Combustion Engine

The term “shell,” as it is used herein, cumulatively refers to thecombination of relatively static features of the internal combustionengine 300 (e.g., crankcase, cam chest, heads, etc.) that supportrelatively dynamic features of the internal combustion engine 300 (e.g.,crankshaft, camshafts, valves, rocker arms, etc.).

V-Configuration Angle

During the pumping process of the internal combustion engine 300, whenthe piston 310 a is furthest away from the cylinder head 340 a, there isoften a clearance problem of the piston 310 a with the piston 310 b andthe bore of the cylinder 320 b, and vice versa. This necessitatesmachining away portions of the pistons and the cylinders in a 45-degreeangle V-configuration engine. Increasing the angle of theV-configuration allows for the pistons to reciprocate freely withoutclearance problems relative to the pistons or bores of the othercylinders. A 90-degree angle V-configuration engine is believed tominimize vibrations relative to a 45-degree angle V-configurationengine; however, for fitment within the frame 100, the preferable angleof a V-configuration engine is from 45 degrees to 60 degrees. Thus,taking into account both fitment and vibration, the angle of aV-configuration engine is preferably near to but less than 60 degrees.

Preferred embodiments of the present embodiment are directed toV-configuration engines having an included angle between two or morecylinders that ranges between about 50 degrees and about 60 degrees.Preferably, the included angle ranges between about 56 degrees and about59 degrees, with a more preferred angle ranging between about 56 degreesand about 57 degrees. Most preferably, the included angle between twocylinders is about 56.25 degrees (See FIG. 4).

The 56.25 degree V-configuration internal combustion engine 300according to the preferred embodiment achieves a number of advantagesover known 45 degree and 90 degree V-configuration engines,including: 1) allowing for piston clearance on long stroke and big boreengine configurations while also allowing for the use of current enginecontrol electronics and software; 2) allowing for less vibration thanthat of a 45 degree V-configuration engine; 3) allowing for easierchassis height fitment than that of a 45 degree V-configuration engineand easier chassis length fitment than that of a 90 degreeV-configuration engine; and 4) allowing for easier fitment of an airintake system than that of a 45 degree V-configuration engine. Accordingto a preferred embodiment, the internal combustion engine 300 displacesbetween about 117 cubic inches (approximately 1900 cubic centimeters)and about 121 cubic inches (approximately 2000 cubic centimeters). Thepreferred stroke of the pistons 310 a, 310 b is between about 4.375inches (approximately 111 millimeters) and about 4.25 inches(approximately 108 millimeters), and the preferred bore of the cylinders320 a, 320 b is between about 4.125 inches (approximately 105millimeters) and about 4.25 inches (approximately 108 millimeters).Thus, the internal combustion engine 300 is preferably “square” (i.e.,the bore-to-stroke ratio is equal to one) or slightly “under-square”(i.e., the bore is smaller than the stroke). However, the bore of thecylinders 320 a, 320 b may also be enlarged, thereby making the internalcombustion engine 300 “over-square” (i.e., the bore is larger than thestroke). Preferably, the ranges of both the bore and the stroke arebetween 4 inches (approximately 101 millimeters) and 5 inches(approximately 127 millimeters), and the range of the displacement isbetween about 100 cubic inches (approximately 1640 cubic centimeters)and about 196 cubic inches (approximately 3210 cubic centimeters).

Another advantage of the 56.25 degree V-configuration internalcombustion engine 300 according to the preferred embodiment is theability to integrate a known engine control software package. Inparticular, the 56.25 degree V-configuration angle is a multiple of11.25 degrees, which is the unit angular measurement when using a“32-minus-2” tooth angular position sensing system. During a singlerevolution, i.e., 360 degrees, of the crankshaft 350, the angularspacing from the rising edge of one tooth to the rising edge of the nexttooth on the known 32-minus-2 timing wheel is 360/32=11.25 degrees,which is precisely one-fifth of the preferred 56.25 degreeV-configuration of the internal combustion engine 300. The preferredincluded angle provides a compact package with complete piston skirtsand cylinders with long strokes and big bores. Advantageously, aV-configuration engine according to the preferred embodiments is notsignificantly taller or wider than conventional engines, and easilyaccommodates engine control software to make the engine control systemeasier to design. A crankcase 380 includes a cam-side portion 380 a anda drive-side portion 380 b that, preferably, are held together by seven,equal length bolts 382. The crankcase 380 defines the included angle ofabout 56.25 degrees between the cylinders 320 a, 320 b according to thepreferred embodiment of the internal combustion engine 300. Inparticular, the crankcase 380 includes a pair of decks 333 a, 333 b,which are machined surfaces against which ends of the cylinders 320 a,320 b are mounted. The decks 333 a, 333 b lie in respective planes thatare oriented at 123.75 degrees with respect to one another, therebyestablishing that the center axes of the cylinders 320 a, 320 b extendat an angle of 56.25 with respect to one another. The cylinders 320 a,320 b can be sandwiched between the crankcase 380 and, respectively, thecylinder heads 340 a, 340 b.

Cylinder Studs

Respective sets of studs or bolts secure the cylinders 320 a, 320 b, thecylinder heads 340 a, 340 b, and the crankcase 380. Referring to FIG. 5,a preferred embodiment includes a first set of five studs 386 thatextend through respective holes 322 in cylinder 320 a, and a second setof five studs 386 extend through respective holes in cylinder 320 b. Theholes 322 extend parallel to a center axis of the correspondingcylinders 320 a, 320 b. Preferably, the holes 322 are disposed aroundthe center axis in a circular pattern that is concentric with the centeraxis. The holes 322 can be disposed equiangularly about the center axis(i.e., every 72 degrees around the center axis), or the holes 322 can bedisposed symmetrically but not equiangularly, or the holes 322 can bedisposed asymmetrically about the center axis (i.e., none of the angularspacing intervals between adjacent holes are equal). According to apreferred embodiment of the internal combustion engine 300, the holes322 in each of the cylinders 320 a, 320 b are disposed symmetrically butnot equiangularly, with the angular interval between adjacent ones of aset of studs ranging between 65 degrees and 80 degrees.

Preferably, each of the studs 386 includes a rod that has threadedsections on either end of an intermediate section 386 a. The diametersand/or the thread pitch of the threaded sections may be similar ordissimilar. A first threaded section 386 b, which is turned into thecrankcase 380, and a second threaded section 386 c, on which a nut isturned against the cylinder head 340, preferably have differentdiameters and different thread pitches. According to a preferredembodiment of the studs 386, the first threaded section 386 b has alarger diameter and a coarser thread pitch than the second threadedsection 386 c, and the intermediate section 386 a has a smaller diameterthan the second threaded section 386 c. The cylinders 320 a, 320 b mayadditionally include passageways for conveying oil between the cylinderheads 340 a, 340 b and the crankcase 380. Preferably, the cylinders 320a, 320 b do not include oil passageways, and oil is instead conveyedbetween the cylinder heads 340 a, 340 b and the crankcase 380 viadedicated oil lines or via separate pushrod tubes 388, which alsoprovide enclosures for the pushrods 364 that actuate the intake valves330 a, 330 b or the exhaust valves 332 a, 332 b.

Cylinder Fins

The cylinders 320 a, 320 b include fins 324 to facilitate air cooling.According to a preferred embodiment, there is a progressive change inthe center-to-center axial spacing between the fins 324. Referringadditionally to FIG. 6, the spacing between adjacent fins is preferablysmaller at a top of a cylinder 320 (i.e., at a location near therespective a cylinder head 340), than at a bottom of the cylinder 320,i.e., proximate the crankcase 380. The increased density of the fins 324at the top places more of the fins 324 at the top, i.e., in the locationof the largest heat source, thereby improving the heat displacementcapabilities of the fins 324. Further, this arrangement also creates aunique appearance that is more aesthetically pleasing and distinctivethan conventional designs.

According to a preferred embodiment of the cylinders 320 a, 320 b, theshape of each of the fins 324 is an annulus that has a generally uniformoutward projection with respect to the center axis of a cylinder 320,preferably to minimize hoop stress. However, portions of one or more ofthe fins 324 can be clipped so as to provide appropriate clearance forother components, e.g., so as not to contiguously engage the pushrodtubes 388 that extend parallel to the cylinders 320 a, 320 b.Preferably, the radial projection of the fin 324 at the top of acylinder 320 is greater than that of a fin 324 at the bottom of thecylinder 320. Preferably, the radial projection of the fins 324 that aredisposed between the top and bottom of a cylinder 320 progressivelyincreases closer to the top of a cylinder 320. The increased surfacearea of the fins 324 at the top is again closest to the location of thelargest heat source, thereby improving the heat displacementcapabilities of the fins 324.

Cylinder Head Fins

Like the cylinders 320 a, 320 b, the cylinder heads 340 a, 340 b alsoinclude fins 344 to facilitate air cooling. Preferred embodiments of thefins 344 on the cylinder heads 340 a, 340 b can have particular shapes,sizes and distributions that correspond to locations of lesser orgreater heat, e.g., around the exhaust port and/or other locations. Thefins 344 can be additionally projected around an exhaust port 346 of acylinder head 340 so as to enhance heat displacement proximate to theexhaust port 346 and thereby improve cooling.

Combustion Chamber Shape and Port Orientation

A combustion chamber has several key design considerations,including: 1) contain the combustion event; 2) promote efficientcombustion; and 3) promote efficient gas exchange. A preferredembodiment combines a unique valve train layout with a uniquewedge-shaped combustion chamber and port orientation.

In many overhead valve pushrod engines, the valves are arranged in aparallel configuration to each other, and are inclined with respect tothe center axis of a cylinder. The resulting shape of the combustionchamber is typically referred to as a “wedge” shaped combustion chamber.Flow into and out of these conventional wedge-shaped combustion chambersis along respective spaced planes that are generally parallel to thelongitudinal direction of the rocker arms. This arrangement provides forsimplicity of construction and ease of manufacture; however, the spacedparallel flow planes of the two valves have several disadvantages,including: 1) the incoming charge is shrouded by the back wall of thewedge thereby creating an obstruction that limits the flow, therebyrestricting power; 2) the incoming charge has a strong tumble motion andvery little swirl, which is believed to be a limitation for good, cleancombustion; and 3) because the flow planes of the two valves are notaligned, scavenging of combustion products in the chamber is lessefficient.

Referring additionally to FIGS. 7-15, flow into and out of a combustionchamber 400 according to a preferred embodiment is generally transverseto the longitudinal direction of the rocker arms 366. In particular,FIG. 13 shows a flow plane including the exhaust port 346 and an exhaustvalve seat 346 a that is nearly perpendicular to the rocker arms 366,and another flow plane including an intake port 348 and an intake valveseat 348 a that is also nearly perpendicular to the rocker arms 366.According to a preferred embodiment, these exhaust and intake flowplanes may be coplanar or nearly coplanar such that there is a spiralflow pattern into the combustion chamber 400, thereby providing improvedmixture preparation for better combustion and more power.

The combustion chamber 400 according to a preferred embodiment achievesa mixture motion that promotes clean, efficient burn and high flow forgood power, and also accommodates the manufacturing simplicity ofparallel intake and exhaust valves 330, 332. This is accomplished by: 1)changing the direction of the incoming and outgoing fluid, as comparedto conventional wedge shaped combustion chambers, to promote a swirl aswell as a tumble in the incoming charge; 2) creating a more straightthrough scavenging flow to better evacuate the combustion products; and3) directing incoming flow away from obstructions, e.g., the wall of thecombustion chamber.

The intake and exhaust ports 346, 348 are arranged in such a manner thatfluid flow is directed through the combustion chamber 400. Instead ofthe incoming charge being directed at the back wall 402 of thecombustion chamber 400, it is directed at an angle across the combustionchamber 400 thereby providing a less restricted path, particularlyduring scavenging. The directed flow in combination with the angle (alsocalled “tilt” or “non-zero acute angle” herein) of the parallel valves330, 332 relative to the center axis of the cylinder 320 creates acombined swirling and tumbling motion, that is very effective at mixingthe fuel and air of the incoming charge, and also evenly mixing anyresidual gases into a more totally homogeneous charge. It is believedthat this homogeneity promotes better combustion by reducing thedetrimental effects of various stratifications of mixture and residualgasses caused when insufficient mixing occurs.

FIGS. 9-15 illustrate details of a preferred embodiment of a cylinderhead 340, including five holes 342 that receive the second threadedsection 386 c of the studs 386, fins 344, the exhaust port 346, theexhaust valve seat 346 a, the intake port 348, the intake valve seat 348a, and the combustion chamber 400.

Press Fitted Two-Piece Main Bearings

A conventional internal combustion engine 300 that has a verticallysplit crankcase 380 typically uses roller bearings to support acrankshaft 350 for relative rotation. FIG. 16 shows a multi-piecebearing assembly 410 according to a preferred embodiment, including abearing split horizontally into two pieces 412 a and 412 b, and acorresponding main bearing cap. Preferably, a multi-piece bearingassembly 410 is press-fitted into either or both of the cam-side anddrive-side portions 380 a, 380 b so as to rotatably support thecrankshaft 350 with respect to of the crankcase 380.

Bolt on Cam Chest for Different Cam Layouts

According to a preferred embodiment, the cam-side portion 380 a of thecrankshaft 350 is coupled to a replaceable cam chest intermediate plate422 that provides different layouts of the valve train, including thecamshafts 360 a, 360 b, 360 c, to be alternatively fitted to the samebasic layout of the crankshaft 350, crankcase 380 and cylinders 320 a,320 b. This allows the internal combustion engine 300 to be adapted todifferent customer needs. The cams, cam drive and heads may vary andresult in aesthetically very different looking engines even though thecore of the internal combustion engine 300 remains similar.

Engine-to-Frame Mount

A preferred embodiment of a front engine-to-frame mounting patternincludes holes 430 a and 430 b that, in comparison to knownarrangements, are widened and moved forward to allow for improvedsupport and strength.

Orientation of the internal combustion engine 300 can be installedupright with respect to the frame 100, or the internal combustion engine300 can be rotated backward about the axis of rotation of the crankshaft350. According to a preferred embodiment, the orientation of theinternal combustion engine 300, when installed in the frame 100, isrotated two degrees backward about the axis of rotation of thecrankshaft 350, and holes 430 a, 430 b are enlarged to accommodatemounting bolts that increase from ⅜ inch to 7/16 inch diameter.

FIGS. 17 a and 17 b show the arrangement of a preferred engine-to-framemounting pattern.

Engine-to-Transmission Mount

Traditionally, when a transmission is relatively close to an engine,known bolt patterns do not allow for the engine-to-transmission bolts tobe easily installed or removed, if access is even provided at all.Referring to FIG. 18, a first preferred embodiment of anengine-to-transmission mounting pattern includes a mounting interface440. Preferably, a transmission side 442 of the engine-to-transmissionmounting interface 440 is contiguously engaged with at least three areasof an engine side 444 of the engine-to-transmission mounting interface440. According to the mounting interface 440, a pattern of bolts thatsecures the transmission 220 to the internal combustion engine 300provides improved bolt clearance with respect to the transmission 220and/or its covers. An engine-to-frame mounting surface may be providedon the crankcase 380 so that the internal combustion engine 300 issupported near the engine transmission interface. Preferably, thismounting surface is on a bottom surface of the engine, and is adjacentto a vertical mounting interface 440. Thus, the mounting surfaceprovides support in a central portion of the engine/transmissionassembly.

A second preferred embodiment of an engine-to-transmission mountingpattern is shown in FIG. 19. A cam-side tab 382 a extends from the rearof the cam-side portion 380 a of the crankcase 380, and a drive-side tab382 b extends from the rear of the drive- side portion 380 a of thecrankcase 380. Holes 384 a and 384 b vertically penetrate the tabs 382a, 382 b, respectively.

An engine-to-transmission mounting plate 450, which is preferably aportion of the vehicle chassis, includes a first set of holes 452 a, 452b and a second set of holes 453 and 454. Preferably, the first set ofholes includes holes 452 a and 452 b that correspond, respectively, toholes 384 a and 384 b. Fasteners, e.g., bolts and nuts, studs and nuts,bolts, etc., extend through corresponding holes. If bolts are used asthe fasteners, one of the holes that receives the bolt includes internalthreads to matingly engage the bolts. Of course, other types of knownfasteners may be used so long as they provide a means of both securelyconnecting the engine-to-transmission mounting plate 450 with respect tothe crankcase 380, and can readily be unfastened so as to separate theengine-to-transmission mounting plate 450 from the crankcase 380.Similarly, fasteners, e.g., bolts and nuts, studs and nuts, bolts, etc.,releasably secure the engine-to-transmission mounting plate 450 withrespect to the transmission 220. According to a preferred embodiment,there are two each of the fasteners and of the holes included in thefirst set of holes 452 a, 452 b, and there are four each of thefasteners and of the holes included in the second set of holes 453, 454.Of course, the number and arrangement of the holes in each of the firstand second sets 452, 453, 454 may be varied so long as theengine-to-transmission mounting plate 450 can be securely and releasablycoupled to the crankcase 380 and the transmission 220.

The engine-to-transmission mounting plate 450 according to the preferredembodiment provides a number of advantages that include making itpossible to adjust the center to center distance between the internalcombustion engine 300 and the transmission 220 for any giventransmission case. Thus, the spacing between the internal combustionengine 300 and the transmission 220, as well as the length of theprimary drive 230, may be selected as desired. In order to minimizeweight and packaging size, the shortest possible combination may beselected, whereas a longer, more spread out package may be selected toenhance aesthetic appeal.

Bolt Patterns and Cover Profiles

According to preferred embodiments, bolt patterns and/or cover profilesof the cylinder stud 386, rocker cover(s) 390, cam chest intermediateplate 422, and camshaft drive chest cover 422 can be selected to achievetheir structural requirements and also provide aestheticcharacteristics. Different appearance covers can be provided for therocker cover(s) 390 or cam chest cover 422. Additionally, the boltpattern maybe varied, such as a four-bolt pattern, a five-bolt pattern,etc. Preferably, the bolt pattern on the cam-side portion 380 a of thecrankcase 380 allows a number of bolts within a range of four bolts toeleven bolts. The bolt pattern on the cam chest intermediate plate 422uses seven bolts, and the bolt pattern on the camshaft drive cover 424uses four bolts.

According to a preferred embodiment, a center crankcase bolt can bedisposed inside the cam chest in the center of the V angle of thecylinders 320 a, 320 b. Placing the center case bolt inside the camchest allows for the cam chest intermediate plate 422 to be extended tothe top of the V on the crankcase 380. FIG. 35 shows a preferredembodiment wherein a single casting can be machined to various lengthsto obtain more than one different size transmissions 220. This isbelieved to simplify manufacturing and reduce raw material inventory.

Power System

The phrase “power system,” as it is used herein, cumulatively refers tothe combination of relatively dynamic features (e.g., crankshaft,connecting rods, and pistons) of the internal combustion engine 300 thatconvert heat energy to rotation. In most internal combustion engines,connecting rod(s) 500 are used to connect and transfer energy frompiston(s) to a crankshaft 350. A “cap” or bottom portion 502 of eachconnecting rod 500 may be split to permit the connecting rods 500 to beclamped around the crankshaft 350. Clamping is typically performed usingone or more rod bolts 504 with corresponding rod bolt nuts 506.Typically, automotive connecting rod bolt nuts 506 are often installedfrom the bottom/cap side of the connecting rod 500. A variation of thisis to install a bolt from the bottom/cap side and have a threaded holein the connecting rod 500. Either method requires access to thebottom/cap side of the connecting rod 500, limits the stroke of theengine, and complicates assembly and repair of the engine.

Inverted Connecting Rod/Bolts

According to a preferred embodiment, a connecting rod 500 includesreversed rod studs/bolts. Because the internal combustion engine 300 hascylinders 320 that separate from the crankcase 380, relatively easyaccess to the topside of the crankshaft 350 is available. If the rodbolt nuts 506 are provided on the top/connecting rod side versus thebottom/cap side, the rod bolt nuts 506 can be accessed through thespigot hole in the crankcase 380. This allows the connecting rod 500 tobe removed while the crankshaft 350 is still in the crankcase 380. Avariation on this is to have a bolt screw into a threaded cap 502.Either method increases clearance inside the crankcase 380 and thereforeallows longer strokes.

Splayed Rod Bolts

According to a preferred embodiment, the connecting rod 500 may includesplayed rod bolts 504. As shown in FIG. 21, rod bolts 504 are at leastpartially rotated by an angle [theta] relative to a longitudinal axis508 of the connecting rod 500, thereby converging toward one another inthe cap 502. As an example, holes for the rod bolts 504 may be rotatedin a range of about 1 degree<[theta]<about 45 degrees. More preferably,the bolt holes are rotated in the range of about 12.5degrees<[theta]<about 17.5 degrees, and most preferably are rotated suchthat [theta]=about 15 degrees. This arrangement can be referred to as aconnecting rod with a “splayed” bolt pattern or a “splayed connectingrod.” Splaying the rod bolts 504 increases clearance inside thecrankcase 380 and allows longer strokes than traditional connecting rodlayouts.

Bolt on Flywheel Mass Internal to the Crankcase

A known V-twin motorcycle engine uses counter-balance shafts to dampenengine vibrations. The counter-balance shafts, which are driven by theinternal combustion engine 300, add complexity and cost to the enginepackage. Instead, according to a preferred embodiment, the crankshaft350 includes a balancing structure 352 for the internal combustionengine 300. In particular, the preferred embodiment of the balancingstructure 352 includes at least one mass 354 that is internally disposedin the crankcase 380 and that reduces vibration of the crankshaft 350.Thus, the balancing structure 352 reduces vibration by increasingcrankshaft mass without adding complex mechanisms, e.g., eliminates acounter-balance shaft and its drive off the crankshaft 350. By addingmass, the magnitude of vibrations can be reduced. Preferably, theadditional mass is added as close as possible to the axis of rotation ofthe crankshaft 350, so as to minimize any increase in rotationalinertia. The rotational inertia that is added can reduce torsionalvibration that can cause additional stresses on other drivelinecomponents, such as the transmission 220, clutch 240, and/or primary andsecondary drive chains/belts. Also, the rotational inertia that is addedmay also improve the launch feel of the engine; and the internalcombustion engine 300 is further less likely to stall due to theincreased rotational inertia and does not require as much throttle inputwhen the clutch 240 is released. Referring to FIG. 20, the crankshaft350 includes a preferred embodiment of a balancing structure for theinternal combustion engine 300. In particular, the preferred embodimentof the balancing structure 352 includes at least one flywheel mass thatis attached to the crankshaft 350 and internally disposed in thecrankcase 380, and that reduces vibration of the crankshaft 350. Theflywheel mass may include one or more removable weights 352 a and 352 b,which can be bolted together with the crankshaft 350 to form anassembly. The removable weights 352 a, 352 b may also be configurablefor different inertial requirements. In particular, different amounts ofvibration and inertia for a given application may be tuned as desired.By using different weights 352 a, 352 b, such tuning ability isprovided. As shown in FIG. 22, another preferred embodiment of thebalancing structure 352 can be manufactured as a one-piece crankshaftwith no detachable masses or rods. The preferred embodiment can alsoinclude a flywheel bolt pattern and design, as shown in FIG. 20, that isconfigured and adapted to bolt on different weights 352 a, 352 b. In aV-twin engine, there are vibrations that are introduced from differentengine components, all of which are linked directly or indirectly to thecrankshaft, and there are also the vibrations that occur due to thecombustion in the engine. With an increased inertia of the crankshaft,the above vibrations are dampened. However, the ideal dampening andresulting vibration that is felt varies in the opinion of the individualusing the engine. By attaching different weights 352 a, 352 b to thecrankshaft 350, many levels of dampening can occur. This allows thecustomer to select the amount of vibration that they feel is idealwithout making several different crankshafts. The increased inertia mayalso improve the launch feeling when used in the motorcycle 20.

The weights 352 a, 352 b are preferably manufactured from a suitablemetal, metal alloy, or composite. The crankshaft 350 and the weights 352a, 352 b may be cast, forged, or machined from stock. A one-piece designis believed to be best for the crankshaft 350; however, the attachableweights 352 a, 352 b allow for one crankshaft 350 to be used in severaldampening configurations. Preferably, the entire crankshaft assembly hasa mass that is as much as 30% or more greater than a conventionalcrankshaft.

Machined Ignition Timing Marks and Crank Position Sensor

According to a first preferred embodiment, a crank position sensor 354is mounted on the cam chest intermediate plate 422 and cooperates with atrigger wheel 356 that is separately mounted on a crankshaft/belttensioner, as shown in FIG. 23. Alternatively, a second preferredembodiment, as shown in FIG. 22, includes the crank position sensor 354mounted inside the cam-side portion 380 a of the crankcase 380 andlooking at trigger marks 358 machined on the side of the crankshaft 350.

Valve Train

The phrase “valve train,” as it is used herein, cumulatively refers tothe combination of relatively dynamic features (e.g., camshafts,tappets, pushrods, rocker arm, poppet valves, and return springs) of theinternal combustion engine 300 that control the flow of combustioncomponents and combustion products with respect to a combustion chamber.

Tri-cam Layout Including Two Exhaust Cams and One Intake Cam

According to preferred embodiments, the motorcycle 20 includes amulti-cam system for the internal combustion engine 300 that providesimproved valve train geometry in a simple configuration. Preferably, atleast three camshafts are used. Most preferably, two exhaust camshaftsand one intake camshaft are used such that the pushrods 364 for theexhaust valves 332 and the pushrods 364 for the intake valves 330 areapproximately parallel to the center axes of the cylinders 320 a, 320 b.

A three camshaft valve train according to preferred embodiments is foruse in an internal combustion engine with reciprocating pistons andpushrods; in particular a V- twin pushrod engine. Most specifically, amotorcycle V-twin pushrod engine. The three camshafts include twooutboard camshafts and one inboard camshaft with respect to theV-configured engine. This allows for the angle of the pushrods that areoperated by the outboard camshafts to be generally parallel to thecentral axes of the cylinders 320 a, 320 b, and allows for the angle ofthe pushrods that are operated by the inboard camshaft to be nearlyparallel to the central axes of the cylinders 320 a, 320 b.

Conventional V-twin motorcycle pushrod engines having one or twocamshafts drive the pushrods at angles that require large forces to openthe inboard and outboard valves. Some of the energy in opening thevalves is lost in the vector components perpendicular to the center axesof the cylinders 320 a, 320 b; for example, it is desirable for thereciprocating forces of the pushrods 364 to be axially oriented parallelto the center axes of the cylinders 320 a, 320 b. According to preferredembodiments of the internal combustion engine 300, this energy loss canat least be reduced for the pushrods 364 that are inboard of theV-configuration angle, and can be minimized for pushrods 364 that areoutboard of the V-configuration angle. Another disadvantage ofconventional single camshaft V-twin motorcycle pushrod engines is theirwidth, which requires a wider stance by the motorcycle rider. Preferredembodiments of the internal combustion engine 300 provide a narrowerengine case, which increases motorcycle rider comfort, by disposing thepairs of intake and exhaust valves for each cylinder 320 a, 320 b in aplane perpendicular to the axis of the crankshaft 350. Anotherdisadvantage of quad-camshaft V-twin motorcycle pushrod engines is thecomplexity of the valve train and the high amounts of friction in thevalve train. Preferred embodiments of the internal combustion engine 300have fewer parts and there is less friction as compared to conventionalquad-camshaft engines.

According to preferred embodiments of a tri-camshaft valve train for usein a pushrod V-twin internal combustion engine 300 of a motorcycle 20,two outboard camshafts and one inboard camshaft are disposed in aV-configured engine, a shown in FIGS. 24 a-24 c. The three camshafts 360a, 360 b, 360 c force the tappets 362 to force the pushrods 364 to forcethe rocker arms 366 to force the valves 330, 332 open against the forceof the valve return springs 368. Using two outboard camshafts 360 a, 360b allows for the associated pushrods 364 to be run at an angle thatminimizes energy loss in opening the corresponding valves 332. Using oneinboard camshaft for both cylinders 320 a, 320 b reduces the energy lossin opening the inboard valves 330 by improving the angle of the inboardpushrods 364 as compared to conventional single or twin camshaft enginedesigns. Energy loss is minimized or reduced by running the pushrods 364at angles that minimize or reduce the force vector componentsperpendicular to the center axes of the cylinders 320 a, 320 b. It isbelieved that preferred embodiments of the internal combustion engine300 provide increased net power output, improved durability, and bettervalve train dynamics.

According to a most preferred embodiment, a pushrod V-twin motorcycleengine having offset cylinders, provides parallel orientation of all ofthe pushrods with respect to their corresponding cylinder, therebyminimizing or eliminating force vector components of the pushrods thatare perpendicular to the central axis of the corresponding cylinder.

According to a preferred embodiment, a tappet cover 362 a (FIG. 3) issecured to the cam-side portion 380 a of the crankcase 380 and holdsdown dowel pins 362 b (FIG. 5) that keep the tappets 362 from rotating.As shown in FIG. 7, a rocker arm alignment device 366 a according to apreferred embodiment maintains the alignment of the rocker arm 366 andprevents rotation of the rocker arms 366 about their studs 366 b due tothe influence of the pushrods 364. Placing the rocker arm alignmentdevice 366 a between adjacent rocker arms 366 holds each rocker arm 366in place. FIGS. 7 and 8 show a preferred embodiment of the rocker armalignment device 366 a, which is held in place by the rocker studs 366 bwith the rocker arms being pivoted on rocker axes that are collinear(more broadly referred to as “parallel” herein).

Camshaft Drive

The phrase “camshaft drive,” as it is used herein, cumulatively refersto the combination of relatively dynamic features (e.g., belts,belt-pulleys or cogwheels, and idlers) of the internal combustion engine300 that convey rotation from the power system to the valve train.

Conventional V-twin motorcycle engines use gears or chains to operatethe camshafts. These gears or chains create significant undesirablenoise, which can be decreased with a belt driven system, and alsotransfer from the camshafts to the crankshaft a significant amount ofharmonics, which can be dampened with the belt driven system.Additionally, lubrication is needed in gear or chain driven systems andcreates a wet environment to work in for servicing the system, whereas abelt driven system eliminates the need for lubrication allowing forservice to be performed in a dry environment.

Belt Drive Configuration

The system of three camshafts 360 a, 360 b, 360 c according to preferredembodiments can be driven with gears, belts, chains or any combinationthereof. There are also various idler pulley and tensioning devicepositions for belt and chain drive systems.

According to preferred embodiments, a belt drive configuration for aninternal combustion engine, especially a motorcycle engine such as apushrod V-twin engine having three or more camshafts, is low cost,easily manufacturable and produces a minimal amount of noise.

Referring to FIG. 25, a timing belt 520 according to a preferredembodiment is provided with at least one idler pulley 524 (preferably atleast two idler pulleys are provided) or a rub block and at least onetensioning device 526. A belt drive system according to preferredembodiments has a number of advantages as compared to a gear drivesystem, including reduced noise and, because the center positionlocations can be more loosely held, the belt drive system also is easierto manufacture.

Turning the camshafts 360 a, 360 b, 360 c requires torque that issupplied by the crankshaft 350, via the camshaft timing belt 520 andcogwheels 522 a, 522 b, 522 c.

Additionally, one or more idler pulleys 524 and a tensioning device 526are used with the camshaft timing belt 520. The tensioning device 526may function automatically or provide a fixed tension setting on thecamshaft timing belt 520.

The camshaft timing belt 520 is looped through the pulley system asshown in FIG. 26 allowing for the crankshaft 350 to turn the camshafts360 a, 360 b, 360 c. The dimensional layout of the camshafts 360 a, 360b, 360 c to each other and the crankshaft 350 may also allow for finemeshed gears to alternatively be incorporated. Referring to a preferredembodiment illustrated in FIGS. 27 a and 27 b, the belt drive system andcamshafts 360 a, 360 b, 360 c are rotatably supported on the cam chestintermediate plate 422 so to provide easy removal of the whole assemblyas a unit, thereby providing improved crankcase access over conventionaldesigns.

According to a preferred embodiment, the belt drive system consists of atiming belt 520, three camshaft cogwheels 522 a, 522 b, 522 c, two idlerpulleys 524, a pinion cogwheel 522 d fixed to the crankshaft 350 and atensioning device 526, all of which are supported on the cam chestintermediate plate 422. The timing belt 520 is preferably constructed asa toothed belt and made from rubber, nylon, Kevlar®, carbon or acomposite compound. The cogwheels 522 a, 522 b, 522 c, 522 d and the camchest intermediate plate 422 are preferably constructed of a suitablemetal or metal alloy, although the cogwheels 522 a, 522 b, 522 c, 522 dmay also be made of a nylon or composite material. The tensioning device526 is preferably automatic to allow for size variations in the beltdrive system components and engine temperature. Preferably, thetensioning device 526 is made of metal, metal alloy, nylon, composite,or any combination thereof. The cam chest intermediate plate 422 ispreferably attached to the cam-side portion 380 a of the crankcase 380directly with fasteners or by sandwiching the cam chest intermediateplate 422 between the cam-side portion 380 a and the camshaft drivecover 424. Advantages of belt drive systems according to the preferredembodiments include: 1) quieter operation of the valve train; 2) the camchest intermediate plate 422 allows for removal of the camshafts as aunit thereby providing improved access to the crankcase 380; and 3) amore lenient tolerance of components than that of a gear drive system.

According to one aspect of the present embodiment, a belt system isprovided with at least one idler pulley (preferably at least two areprovided) or rub block and at least one tensioning device. The beltdrive system reduces noise when compared to a gear drive system. Becausethe center position locations can be more loosely held, this system alsois easier to manufacture than a gear drive system. The center locationscan be selected so that, for a performance racing version, adapting agear drive uses commonly produced pitch diameter gears.

FIGS. 25A-25C show an alternative camshaft support plate 422A (alsocalled “cam chest intermediate plate”) and camshaft drive system using acombination belt drive with intermeshing camshaft gear drive.Specifically, FIG. 25A (taken from page 67 of provisional applicationSer. No. 60/628,541, from which priority is claimed herein) discloses analternative camshaft drive system where intermeshing gears on thecamshafts engage each other in a first plane, and a center camshaft isdriven by a belt drive extending around the crankshaft pulley in asecond plane parallel the first plane. The three camshafts are supportedon one end by an alternative arch-forming camshaft support plate 422A(FIG. 25B, taken from page 79 of the provisional application Ser. No.60/628,541) and driven by a belt drive extending from the crankshaftpulley located outside the camshaft support plate 422A (see FIG. 25A).An end cover 422B covers the gear arrangement, with the belt and drivepulley being located outside the illustrated cover 422B (FIG. 25C, takenfrom page 232 of provisional application Ser. No. 60/628,541).Alternatively, the cover 422B can be constructed as a cam chestintermediate plate.

Induction System

The phrase “induction system,” as it is used herein, cumulatively refersto the combination of static and dynamic features (e.g., intakemanifold, throttle body, and fuel injectors) that prepare and supplycharges of combustion components to the internal combustion engine 300.

A known V-twin motorcycle engine uses a short, direct intake manifoldwith an air box positioned upstream from the intake manifold. Thisresults in significant undesirable noise transmission that is reduced bya baffling system according to preferred embodiments. A known V-twinmotorcycle engine fitted with fuel injection has a throttle body that isa separate piece from the intake manifold. According to preferredembodiments, a throttle body is integrated in a single piece with theintake manifold.

Air Intake System

A preferred embodiment of an air intake system 540 includes two or moreair passages 542 a and 542 b that draw air from multiple sides of theinternal combustion engine 300. In particular, a preferred embodimentprovides an intake system 540 of a V-twin internal combustion engine 300that is easily packaged and limits the amount of intake noise that istransmitted from the air intake system 540. The air intake system 540can also provide air passages 542 a, 542 b that share a common wall(s)with a throttle body 544. Such an air intake system 540 may also combinean intake manifold 540 a, the air passages 542 a, 542 b and the throttlebody 544 into a single piece. Additionally, preferred embodiments of anair intake system 540 can draw air from either or both sides of theinternal combustion engine 300. Preferably, the air passages 542 a, 542b define a relatively long and tortuous path through which noise musttravel before it can leave the intake manifold 540 a. Preferredembodiments of air intake systems 540 that include dual side intakes canalso have a butterfly valve 546 that provides a direct path to thethrottle body 544 for maximum performance. A preferred embodiment of thebutterfly valve 546 can be controlled electronically or by intakevacuum. FIG. 28 shows an air intake system 540 according to a preferredembodiment with air entering on the left side and passing around thethrottle body 544. An air intake system 540 according to anotherpreferred embodiment includes dual side intakes.

Preferred embodiments of an air intake system 540, particularly for aV-twin motorcycle engine, include an intake manifold 540 a that allowsair to be drawn from one or more locations and directed to the cylinderheads 340 a, 340 b. This allows for lower pressure drops across an airinlet 548 a, 548 b, while minimizing noise transmitted in the air intakesystem 540. The intake manifold 540 a according to the preferredembodiments is easily packaged and limits the amount of noise created bythe air intake system 540.

A preferred embodiment of an air intake system 540 provides air forcombustion in the internal combustion engine 300. Typically, there issignificant noise caused by the flow of air though the air intake system540, in general, and the intake manifold 540 a, in particular. Accordingto preferred embodiments, baffles 550 within the intake manifold 540 alower noise due to airflow in the air intake system 540. In particular,beginning at mating surfaces with air inlets 548 a and 548 b, the intakemanifold 540 a includes the throttle body 544 and one or more baffles550, which run to mating surfaces with the cylinder heads 340 a, 340 b.The baffles 550 can optionally be sealed from ambient air. If thebaffles 550 are sealed from ambient air, air enters the intake manifold540 a from a single location. If the baffles 550 are not sealed fromambient air, then a second air inlet 548 a, 548 b, an additionalthrottle body 544, or both can provide a decrease in the pressure dropfrom ambient air to the mating surfaces with the cylinder heads 340. Inthe latter case, air enters the intake manifold 540 a from two or morelocations. The additional throttle body 544 can be controlledelectronically or by intake vacuum. The intake manifold 540 a can bespecifically designed to be disposed in the V-angle between the cylinderheads 340 a, 340 b without hindering access to any other parts of theinternal combustion engine 300 that would otherwise normally be exposed.Preferably, the air passages 542 a, 542 b that are incorporated into theintake manifold 540 a can share a common wall(s) with the throttle body544 and/or each other. The intake manifold 540 a is preferablyconstructed from a suitable metal, metal alloy or composite material,and it may be cast, forged or machined from stock.

According to preferred embodiments of the air intake system 540,particularly for a V-twin motorcycle engine, the intake manifold 540 aattaches to the cylinder heads 340 a, 340 b using flanges that areeither part of the manifold or individual pieces.

Direct Mounting of a Fuel Injector to the Cylinder Head

Preferred embodiments can also mount a fuel injector 560 on or withineach of the cylinder heads 340 a, 340 b, such as a motorcycle cylinderhead. In particular, each of the cylinder heads 340 a, 340 b is providedwith a corresponding fuel injector 560 mounted directly thereon ortherein. It is believed that mounting the fuel injectors 560 on or inthe cylinder heads 340 a, 340 b provides more precise aiming of the fuelinjectors 560 and simplifies the overall machining requirements forengine fabrication. In conventional engines, the fuel injectors (ifprovided) are typically mounted on the intake manifold. Moving the fuelinjector mounting structure from the intake manifold 540 a, which maynot otherwise need to be machined, to the cylinder heads, which alreadyrequire machining, can eliminate the need for an additional machiningoperation, i.e., on the intake manifold 540 a, thereby reducing thecomplexity and fabrication cost of the intake manifold 540 a and theinternal combustion engine 300. Many known cylinder heads alreadyrequire complex machining, and as such, adding a fuel injector mountingstructure does not significantly increase the fabrication costs of thecylinder heads. Moreover, according to a preferred embodiment, amounting structure 562, which can be a hole, threaded hole, flat pad,etc., for the fuel injectors 560 can be located at standard cylinderhead machining centers, which further reduces the minimal added cost offabricating on cylinder heads 340 the mounting structure for a fuelinjector 560.

The mounting structure 562 is preferably located adjacent to the intakeport 348 of the cylinder head 340, and the fuel injector 560 is securedwith the mounting structure 562. According to the preferred embodiments,the fuel injector 560 discharges fuel into the air stream that flowstoward the intake valve 330 and into the cylinder 320.

Engine Control Unit Mounting

Referring to FIG. 29, preferred embodiments include providing an enginecontrol unit mount 570 on an intake manifold 540 a, such as the intakemanifold 540 a of the internal combustion engine 300 for a motorcycle20. Mounting an engine control unit 572 to the intake manifold 540 areduces wiring on the motorcycle 20 because many of the sensors, e.g.,air temperature, throttle opening, etc., that supply information to theengine control unit 572 are located in the vicinity of the intakemanifold 540 a. Additionally, mounting the engine control unit 572 tothe intake manifold 540 a makes the engine control unit 572 an integralpart of the internal combustion engine package, thereby making engineinstallation more turnkey. The engine control unit 572 can be mounted tothe bottom of the intake manifold 540 a, but the particular location andorientation of the engine control unit 572 with respect to the intakemanifold 540 a can vary, e.g., in accordance with packaging requirementsfor the internal combustion engine 300. It is also envisioned that theengine control unit 572 could be mounted inside the intake manifold 540a such that the structure of the intake manifold 540 a could shield theengine control unit 572 from ambient conditions exiting outside theintake manifold 540 a.

Air Inlet Covers

According to a preferred embodiment, the air inlets 548 a and 548 b,which can be disposed on either or both sides of the internal combustionengine 300, include a substantially teardrop shape.

Alternatively, the air inlet 548 a can be disposed on one side of theinternal combustion engine 300, and an air box having a substantiallysimilar appearance as the air inlet 548 a can be disposed on the otherside of the internal combustion engine 300.

Lubrication System

The phrase “lubrication system,” as it is used herein, cumulativelyrefers to the combination of features (e.g., oil pump, oil filter, andoil flow passages) that facilitate reduction of friction at interfacesbetween relatively dynamic and static features of the internalcombustion engine 300.

Oil Pump Design and Method of Delivering Oil

According to a preferred embodiment, an oil pump 580 pressurizes alubricant, e.g., oil, synthetic oil, etc. for dispersement at theinterfaces between the relatively dynamic and static features of theinternal combustion engine 300, and particularly a V-twin internalcombustion engine of a motorcycle 20.

A known motorcycle engine includes holes drilled in the cylinder headsand crankcase to provide a path for lubricant to return to the sump. Itis believed that drilled holes increase the cost and complexity ofmanufacturing the cylinder heads and crankcase. As such, a need existsfor an improved oil passage.

According to a preferred embodiment, a lubrication system includes theoil pump 580 installed over the crankshaft 350; oil passages 582disposed within a housing 580 a of the oil pump 580; a scavenge port 584disposed on the bottom of the pump housing 580 a; and gear rotors 586and separator plates 588 of the oil pump 580.

According to a preferred embodiment, the oil pump 580 distributes viasupply passages 590 a, 590 b and 590 c pressurized lubricant as requiredthroughout the internal combustion engine 300, and collects via returnpassages lubricant to be recirculated by the oil pump 580. Preferably,the supply 590 a, 590 b, 590 c and return passages deliver lubricantbetween the cylinder heads 320 and a sump in the crankcase 380.

According to a preferred embodiment, the supply passages 590 a, 590 b,590 c are cast into the crankcase 380. It is believed that casting thesupply passages 590 a, 590 b, 590 c in the crankcase 380 reducesdrilling operations and reduces or eliminates the need for externalplugs that are necessary in a known lubrication system that uses drilledpassages. FIGS. 32 a and 32 b show the supply passages 590 a, 590 b, 590c, which are preferably steel, cast into the cam-side portion 380 a ofthe crankcase 380.

Alternatively, in lieu of in-casting all three of the supply passages590 a, 590 b, 590 c, the supply passage 590 c can be drilled and theother two supply passages 590 a, 590 b remain in-cast. Insofar as thesupply passage 590 c extends linearly for only a short distance,drilling the supply passage 590 c can be more cost effective.

Also, the other two supply passages 590 a, 590 b can be simplified byreducing the number of bends along their length.

Oil Pump Attached to the Crankcase

According to an alternate preferred embodiment of the oil pump 580′ forthe internal combustion engine 300, the oil pump 580′ is supported withrespect to the crankcase 380 by an oil pump mount 386 that provides asmall tolerance stack-up in a location where there is minimal deflectionof the crankshaft 350. For example, the oil pump 580′ is preferablymounted on or attached to the crankcase 380 such that the oil pump 580′is disposed relatively close to the main bearing assembly 410. The oilpump mount 386 is believed to reduce position tolerance problems causedby a known mounting structure that supports an oil pump assembly on acamshaft support plate. The oil pump 580′ can be supported via the oilpump mount 386 on the crankcase 380.

Mount for an Oil Pressure Sensing Unit and an Oil Filter

FIG. 33 shows a preferred embodiment of an oil pressure-sensing unit 594(also called “oil pressure sensor) this positioned on or near a filtermount 596 for an oil filter 598. Preferably, the filter mount 596arranges the oil pressure sensor 594 in a substantially parallelorientation with respect to the oil filter 598, thereby simplifying therequired machining. Similar to the mounting structure 562, additionallymachining the filter mount 596 to accommodate the oil pressure sensor594 is preferable to machining another part that otherwise would notrequire machining except to accommodate the oil pressure sensor 594.According to a preferred embodiment, the oil filter 598 is disposed infront of the internal combustion engine 300 and below the front enginemount so as to substantially hide the oil filter 598 from view, andthereby provide a more aesthetically pleasing appearance of the internalcombustion engine 300. Further, this location reduces or eliminates oildrippings onto either the front engine mount and/or electricalcomponents in the vicinity of the front engine mount. As compared to anoil filter mounting location on a known engine, the location formounting the oil filter 598, which is rotated down and back, providesimproved access to the bolts for the front engine mount.

Pushrod Tubes Providing Oil Return Passages

According to a preferred embodiment, the return passages can include thepushrod tubes 388. The pushrod tubes 388 can be used in conjunction withor as alternatives to drilling holes in the crankcase 380, as waspreviously described with respect to the supply passages 590 a, 590 b,590 c. If the pushrod tubes 388 are used without the drilled holes, thecost and complexity of manufacturing the cylinder heads 340 and/or thecrankcase 380 can be reduced. One or more pushrod tubes 388, which maybe oversized in comparison to traditional pushrod tubes, provideadditional area around the pushrods 364 for the passage of oil or air.FIG. 34 shows the internal combustion engine 300 including pushrod tubes388 for returning oil to the sump in the crankcase 380. According to apreferred embodiment, O-rings seal the pushrod tubes 388 with respect tothe crankcase 380 and cylinder head 340.

Reed Valve Flapper Position, Size and Function

FIG. 35 shows a preferred embodiment for the location and mounting of acrankcase reed valve configuration 600 for removing oil from a flywheelcavity 602 using airflow and pressure created by virtue of the reedvalve assembly 600 separating a cam chest 420 from the flywheel cavity602. The oil is then scavenged out of a cam chest 420 by the oil pump580. According to a first preferred embodiment, the reed valve assembly600 includes four reed valves mounted on a reed cage. The reed cage isthen pressed into the crankcase 380 inside the cam chest 420. A singlescrew can be installed to stop the reed cage from rotating with respectto the crankcase 380. According to a second preferred embodiment, thepressed-in reed cage, and two of the four reed valves, are eliminated.And according to a third preferred embodiment, the two reed valves arecondensed into one, wider reed valve and two holding screws are providedto stop the single reed valve from rotating.

Preferably, the shape of the cam chest 420 changes for the differentconfigurations of the reed valve assembly. For example, a separatecompartment can be provided with the reed valve(s) mounted inside, orthe pocket height can be varied with respect to the cam chest 420 so asto provide a smaller, symmetric cam chest 420.

Vehicles Including an Internal Combustion Engine

Vehicles 1 according to preferred embodiments include a chassis 3 and apropulsion system 5 driving the vehicle 1. Preferably, the chassis 3provides a platform that is suitable for an intended environment (e.g.,land, air, water, etc.) and may support an operator, and the propulsionsystem 5 includes an internal combustion engine 10, a transmission 12(e.g., providing one or more engine speed changing ratios), and anoutput device 14. Examples of vehicle types using propulsion systemsaccording to the preferred embodiments may include motorcycles, allterrain vehicles, utility vehicles, riding lawn mowers, passenger cars,cargo tracks, snowmobiles, half-tracks, tracked vehicles, amphibiousvehicles, personal watercraft, boats, and light-sport aircraft such asan ultralight.

Classification as a particular type of vehicle 1 may be made on thebasis of characteristics such as the nature of how the chassis 3receives the operator (e.g., operator rides-on, operator is enclosedwithin, etc.), the control interface between the vehicle 1 and theoperator (e.g., handle bars versus steering wheel, accelerator pedalversus twist grip, etc.), and the interaction of the output device 14with the intended operating environment (e.g., one or moreground-engaging driven wheel(s), traction belt, propeller, etc.).Referring to FIGS. 36 a and 36 b, various features and advantages of thepresent invention will now be explained with respect to the motorcycle20, but are also applicable to the other types of the vehicle 1.

The motorcycle 20 preferably includes a frame 100, a fork 120 supportinga front wheel 122, a swing arm 130 supporting a rear wheel 132, a seat140, a fuel tank 150, an oil tank 160 and a power train.

The fork 120 is pivotally supported with respect to the frame 100 andconnected with a set of handlebars 124 for steering the motorcycle 1.The rear wheel 132 is driven by the power train. The seat 140 providessupport for the operator, and tanks 150, 160 supply fuel and oil to thepower train.

The power train conveys rotation to the rear wheel 132 via a secondary210 driven by the output of a transmission 220. The secondary 210 mayinclude a chain drive secondary, a shaft drive secondary or a belt drivesecondary. Preferably, the secondary 210 includes a chain coupling adriving sprocket 214 fixed to an output from the transmission 220 and adriven sprocket 216 fixed to the rear wheel 132.

The internal combustion engine 300 conveys rotation to the transmission220 via a primary 230 and a clutch 240. The primary 230 may include abelt drive primary or a chain drive primary.

While the present invention has been disclosed with reference to certainpreferred embodiments, numerous modifications, alterations, and changesto the described embodiments are possible without departing from thesphere and scope of the present invention, as defined in the appendedclaims. Accordingly, it is intended that the present invention not belimited to the described embodiments, but that it have the full scopedefined by the language of the following claims, and equivalentsthereof.

What is claimed is:
 1. An internal combustion engine comprising: atleast two cylinders; a piston in each of the cylinders; a crankshaft formoving the pistons; a crankcase containing the crankshaft; threecamshafts; a cam chest intermediate plate supporting the camshafts; anda drive system for rotating the camshafts including a camshaft cogwheelon each of the camshafts, a pinion cogwheel on the crankshaft, and atleast one timing drive component driven by the pinion cogwheel anddriving the camshaft cogwheels.
 2. The internal combustion engine ofclaim 1, including only the three camshafts.
 3. The internal combustionengine of claim 1, wherein the at least one timing drive componentincludes one or more of a chain, belt, and gears.
 4. The internalcombustion engine of claim 3, wherein the at least one timing drivecomponent includes a continuous belt that engages the camshaft cogwheelsand the pinion cogwheel.
 5. The internal combustion engine of claim 1,wherein the cam chest intermediate plate is attached to a cam drive sideportion of the crankcase.
 6. The internal combustion engine of claim 1,including at least one idler pulley.
 7. The internal combustion engineof claim 6, wherein the at least one idler pulley includes two idlerpulleys.
 8. The internal combustion engine of claim 1 including atensioning device in-line with the at least one timing drive component.9. The internal combustion engine of claim 1, wherein the drive systemincluding the camshafts and the camshaft cogwheels can be removed alongwith the intermediate plate from the crankcase as a unit.
 10. Aninternal combustion engine comprising: at least two cylinders eachdefining an associated longitudinal direction and combining to define aV-shape; a piston in each of the cylinders; a crankshaft for moving thepistons; a crankcase containing the crankshaft; three camshafts; a camchest intermediate plate supporting the three camshafts; and a valvetrain system including tappets and pushrods engaging the threecamshafts, rocker arms engaging the pushrods, and intake and exhaustvalves engaging the rocker arms, the intake and exhaust valves beingoperably connected to an associated one of the at least two cylinders;the pushrods extending in a direction parallel to the longitudinaldirection of the associated cylinder; and a drive system driven by thecrankshaft for rotating the three camshafts.
 11. The internal combustionengine of claim 10, wherein the drive system includes at least one of achain, belt, or gears.
 12. The internal combustion engine of claim 10,wherein the drive system comprises a continuous belt.
 13. The internalcombustion engine of claim 12, wherein the continuous belt is a toothedbelt and made from a material including at least one of rubber, nylon,Kevlar®, carbon and composite compound.
 14. The internal combustionengine of claim 10, wherein the cam chest intermediate plate is attachedto a cam side portion of the crankcase.
 15. The internal combustionengine of claim 10, wherein the at least one idler pulley includes twoidler pulleys.
 16. The internal combustion engine of claim 10, whereinthe drive system including the cam chest intermediate plate and thecamshafts can be removed from the crankcase as a unit.
 17. In aninternal combustion engine having cylinders, pistons, a crankshaft formoving the pistons, and camshafts for moving valves controlling fluidflow into and out of the cylinders, an improvement comprising: thecamshafts includes three camshafts; and a cam chest intermediate platesupporting the camshafts; the intermediate plate being attached to acamshaft portion of the engine.
 18. The improvement of claim 17,including a camshaft cogwheel on each of the camshafts and a pinioncogwheel on the crankshaft, and at least one timing drive componentdriven by the pinion cogwheel and driving the camshaft cogwheels.